Wireless data networks serve wireless telephones with mobile data services like internet access, voice calling, and Short Message Service (SMS). The wireless data networks have wireless access points that exchange user data over the air with the wireless telephones. The wireless telephones are usually mobile and access the internet, make calls, and send messages from various geographic locations. Tracking the location of an individual wireless phone is important during emergencies and other situations. The geographic location of the wireless access point which currently serves the wireless phone is often used to estimate the location of the wireless phone.
To send an SMS message, the wireless phone first establishes a bearer connection over a wireless data network to an Internet Multimedia Subsystem (IMS). The wireless phone transfers the SMS message to the IMS in a Session Initiation Protocol (SIP) message. The SIP message has a mark that indicates the internal SMS message. The SIP message also has a Private Access Network Information header that contains the identity of the wireless access point which currently serves the wireless phone. The IMS detects the presence of the SMS message and forwards the SIP message to an SMS Center (SMSC). The SMSC extracts the SMS message from the SIP message, and if the SMS message is not an emergency message, the SMSC authorizes the wireless phone for the SMS and transfers the SMS message toward the destination. To transfer the SMS message, the SMSC generates a Short Message Peer-to-Peer (SMPP) message and transfers the SMPP message containing the SMS message to an SMPP gateway. The SMPP gateway delivers the SMS message to the destination—often over an additional SMPP gateway, IMS, and wireless data network.
If the SMS message is an emergency message, the SMSC skips authorization and transfers the emergency SMS message in an SMPP message to a Public Safety Answering Point (PSAP) gateway—which is a special type of SMPP gateway. The PSAP gateway receives the SMPP message having the emergency SMS message and interacts with a network location platform that locates the wireless telephone for the PSAP gateway. The PSAP gateway then selects a PSAP based on the location of the wireless phone. The PSAP gateway then transfers the emergency SMS message to the selected PSAP. The selected PSAP interacts with a location server to locate the wireless phone that transferred the emergency SMS message. The selected PSAP then directs emergency personnel to the location of the wireless phone.
Unfortunately, the PSAP gateway first interacts with the network location platform to locate the wireless telephone before connecting to the PSAP. Moreover, some wireless telephones may not properly support location services from the network location platform.